Once you have eliminated the impossible
by CeridwenAeradwer
Summary: A trainee warlock at the coven which Willow is also staying at is found brutally murdered. Flayed alive. Knowing Willow's dark past, both the coven and Watcher's council quickly turn on her but Sherlock is convinced of her innocence, finding himself drawn into an impossible supernatural world as he struggles to solve the uniquely dangerous case.


**Takes place post-BTVS season 6, and pre-Sherlock season 1**

* * *

Chapter 1: Here we are again

Willow stared blankly down at the handcuffs wrapped around her wrists, looped under the bar nailed to the cold, white table. They may as well have been made of straw for all the good they did of holding her still, but judging by the veritable battalion of Witches and Warlocks casting her suspicious glances that she had seen scattered throughout the police station, someone had already considered that.  
Everyone thought she was guilty, Willow realised gloomily. Except Giles. He knew how hard Willow had worked to get to where she was now, how much better she had been doing, but even he had looked straight to her when the body was found. That had hurt.

Luciel had been a young trainee warlock. At eighteen years old he wasn't particularly strong or skilled, but honest and quiet and hardworking nonetheless. What reason could they possibly come up with for Willow killing him? She never even talked to the boy, for crying out loud!

If she was found guilty, would they kill her? They must know prison could not hold her, and even if she was willing to serve her time they wouldn't risk her getting free. Would they put her out of her misery? Concoct some spell to hold her? Neither sounded like a fate she would particularly enjoy.  
Of course… she couldn't exactly claim she didn't deserve it. Even if sentenced for the wrong crime, she was still a murderer. Perhaps the time had finally come to pay...

* * *

Lestrade spent more time than he liked to admit staring at the door to 221B Baker Street. He had lost count of the number of times he had come crawling to Sherlock's door with an impossible case, begging him to do his job for him. At least, that's how Donovan and Anderson always put it…

No. He shook himself. Every detective needs a consult now and then. It's not as though he _always_ relies on the sociopath, and he had plenty of solved cases of his own behind him. If anything, watching the man at work starts you thinking in new ways yourself, noticing little details, thinking around a problem rather than through it. Making little jumps that other's can't see. Even if he was nowhere near the level of Sherlock's observational prowess, Lestrade had noticed small changes in how he tackled his own cases over the years. It was a learning experience.

Besides, everyone agreed that there was something just plain weird about this one. It was right up Sherlock's street.

There was nothing to be ashamed of.

Satisfied with this reasoning, he steeled himself and rapped sharply on the door. Muffled footsteps edged closer and suddenly the door was pulled ajar, waves of faint yet eloquent violin music wafting through the gap.

The kindly face of Mrs Hudson, the landlady, appeared around the door.

"Oh, Inspector!" She exclaimed happily, opening the door fully and moving out of the way as she motioned for him to come in. "Another murder is it then?" She said a shade too brightly as Lestrade hurriedly stepped inside and brushed off the worst of the rain. "Nothing too grisly, I hope. Last time I found him stuffing severed fingers into a teacup over a Bunsen burner. "Testing the heat capacity of flesh" or some nonsense. Well, he can do what he likes when he gets his own crockery, but I'll not be having melted flesh on my tablecloth, thank you very much! I had enough of that sort of thing back when my husband-"

"-Yes! Alright." Lestrade interrupted, growing a little disturbed. Mrs Hudson was a lovely woman, accommodating and thoughtful, but now and then little details which you would rather not know about would occasionally surface.

"It's… it's no worse than normal, I promise." He lied. "Is he…?"

Mrs Hudson nodded. "He's upstairs. He's been awfully bored of late, so he should be happy to see you." She said, pointing to the room above.

The music grew louder as Lestrade ascended the stairs, the old floorboards creaking under his shoes. He noted somewhat glumly that the door had been unlocked and very purposefully left open, despite the fact that music had not paused since he stepped into the house.

 _He knew I was coming, didn't he? I'm getting sick of this…_ He thought as he moved inside.

Sherlock stood facing the window, gazing out at the London streets as his fingers and bow danced over the strings of his violin. Lestrade stood awkwardly inside he door, reluctant to interrupt.

Eventually, he nervously cleared his throat.

"Sherlock-"

"No. Shut up." Sherlock replied bluntly, not turning around. The melody continued to swell and grow, never once faltering and the notes weaved and shimmered in the air.

Lestrade grit his teeth in annoyance. This was police work, and despite his brilliance Sherlock did not get to dictate when it was done.

"Sherlock, I really have to-"

"You are not in a hurry, Inspector, else you would have put on the sirens on your way here and you certainly would not have spent the better part of ten minutes staring at the front door. I got bored waiting for you to come in, so you can now wait for me. Therefore, I will ask you again; shut up."

Lestrade refrained from pointing out that the way he had phrased that last sentence made it less of a request and more of an entitled demand, but only just. Instead he contented himself with glaring at Sherlock's back and leaned against the doorframe, crossing his arms, as he waited for him to finish. As annoyed as he was, he had to admit: the music was beautiful. It was a smooth and elegant symphony, practised to perfection. Not for the first time Lestrade found himself wondering what exactly a man of Sherlock's talent and intellect was doing solving crimes for the police, getting nothing in return.

Eventually, the music faded and finally stilled. As soon as the last note fell rom the strings, Sherlock whisked the instrument away from his chin and tossed both violin and bow haphazardly onto the already cluttered desk.

"Right then!" He said brightly, pushing past Lestrade and all but skipping down the stairs. "Shall we be off then?"

Lestrade blinked in surprise at the sudden change. "Be off? But you don't even know… Oh, bloody hell… look who I'm talking to." He finished in a resentful mutter. He gave the apartment a final glance, before gently pulling the door closed and following Sherlock down the stairs.

* * *

It seemed like an eternity Willow was locked in that dull little room. Her hands were itching and bristling with magic, longing to break free of their constraints. Willow closed her eyes and with a practised determination, pushed the feeling away to the back of her mind. No good would come of that. She knew it. Using magic around those who were... inexperienced with the supernatural was never a good idea, and besides, such action would only confirm her guilt to the other members of the coven. If that happened, they would never give her another chance. She could never go back to Sunnydale.

Her hands clenched into fists. She'd wait this out. She had to.

The door swung open suddenly, causing Willow to jump. She cursed inwardly as a charged spark jumped from her hand and fizzled briefly in the air, but the two men walking in appeared not to notice. She clasped her hands together and focused on subduing the torrents of dark magic that were beginning to surge through her veins

"Miss Willow Rosenberg, right?" The first, a man somewhere in his late forties, addressed her. She nodded nervously. He took a seat and motioned first to himself and then his companion. "I'm Detective Inspector Lestrade, and this is consulting detective Sherlock Holmes."

The second man was taller and younger than the first, taking a seat next to the Inspector.

Willow's mouth twitched into a polite, if impatient, smile. "Yeah, okay, hi." She tugged gently at the handcuffs. "Are these really neseccary? Like, am I actually being arrested?"

Sherlock cast a sideways glance at his friend. "Yes, I was just wondering about that. It's a bit early to be making such an arrest, and if you already have a likely suspect, what do you need me for?"

Lestrade shifted uncomfortably. "Well, it's… a bit of an unusual scenario, to be honest. And for some reason I've had strict orders to keep you under close guard."

Willow's eyes widened briefly, and then a sorrowful feeling bubbled up through her chest. Of course the Watcher's council would be aware of what was going on, and she wouldn't put it past them to have a few strings to pull in the English police force. They knew stress and anger could bring her magic to the surface, so surely they wouldn't resort to keeping such a tight guard on her if they didn't have to. If they really thought she was guilty…

This could be very bad indeed.

Across the table, Sherlock's eyes narrowed as he observed Lestrade's discomfort and Willow's reaction. There had been more people than normal walking around the station when they entered, and try as they might to appear otherwise, very few of them were civilians. There was no evidence against this woman that he could see, and if he couldn't see it then it was likely that none existed. She had no criminal record at all, and yet she was being treated as a dangerous thug.

Someone, for some reason, was very scared of Miss Rosenberg.

 _Interesting_

Lestrade cleared his throat. "Right. Well, let's get on with it. Firstly, how well did you know Luciel Howe?" He asked.

"I didn't. I mean, I've seen him around and I knew his name, but we never actually talked."

"And… what do you know about how he died?"

Sherlock watched Willow closely for her next answer. This was the interesting part of the case. The boy had been flayed alive. It was a masterful job, carefully done, with the skin left draped neatly over a nearby chair. Molly had insisted that not only had the boy been alive and concious when it had happened, but that the actual skinning had all been done within seconds. If it hadn't been Molly doing the autopsy, Sherlock would have dismissed this as impossible. There was no way such a… well, let's face it, _masterpiece_ had been created in anything under an hour. At least.

And yet… it had been.

Willow shook her head. "Not much, I just heard that it was something pretty bloody. I was just walking to the hall for classes, people were gathered outside talking about it, the police arrived, and… well…" She rattled the handcuffs again. "I've been here ever since."

"Yes… everyone there seemed pretty quick to accuse you. Do you know wh-?"

Sherlock cut him off by slamming his palm down on the table. "No! Boring question!" He exclaimed.

Lestrade glared at him. "Sherlock!" He reprimanded, but the consulting detective ignored him and leaned forwards.

"No no no, that's not a good question at all, is it? Here's a good question; Why are you in England, Willow?"

Willow hesitated, then frowned. "Um. What?"

"It's a simple enough question, isn't it? A good one though. You had a good life in California. Close friends, brilliant grades both at school and university-,"

"-College." Willow briefly interjected. Sherlock ignored her.

"-particularly good computing skills, plenty of job prospects. Distant or absent parents, admittedly,-"

"-Hey, how did you-?"

"-But nothing that would account for a sudden and semi-permanent departure to a foreign country where the only contact you have is your old highschool librarian."

Willow was staring at him. She subtly sat further back in her seat, as if trying to put some distance between them. The silence stretched between them for a moment longer than it should have.

"Giles is a friend." She said at last. "He was sort of a mentor to me and my friends at Sunnydale High. He knew somewhere I could do some further studying so-"

"-No. No. That's not it." He narrowed his eyes. "Something happened in Sunnydale, didn't it? You're running from something. And whatever it is you're running from has a lot of people very nervous."

Even as he said it, he knew that he was missing something, that somehow he was ever so slightly off the mark. However, judging from how Willow's jaw clenched and her eyes darted around the room like a trapped animal, he wasn't too far wrong.

Willow's hands were shaking now. Very subtly, but it was there. Was it fear? Anger? Something else? Sherlock scrutinised her face for hints. She was naturally quite pale, but there was something more than that there now. A sort of pallid sheen to her skin, and faint circles under her eyes. Her brow slightly furrowed in… concentration? Or pain?

 _Drug withdrawal, perhaps?_

Sherlock was no stranger to the effects of withdrawal, and he knew the signs well. Some of them were present and yet somehow… it still didn't quite fit.

What was he missing?

"…Right." Lestrade said slowly, glancing from Sherlock to Willow and back again. "Anyway… back to the case,"

Sherlock looked round in puzzlement. "What are you talking about? This is the case."

"No, it's not. The case is about the poor bloke found in a pool of his own blood, not Miss Rosenberg's... accommodation or education." He said firmly. Sherlock opened his mouth to retort but Lestrade shot him a fierce glare. Sherlock gave a childlike scowl in reply and leaned back from the table.

"Fine. Don't mind me." He said, taking his mobile phone out from his pocket.

Willow arched an eyebrow. These two had a… an interesting dynamic.

Lestrade sighed. "Right. Thank you." He turned back to Willow, smiling in slight embarassment. "Right. Er. Yes. Many people present seemed quick to point the finger at you. If that isn't true, do you have any explanation for why they would say that? Is there anyone who might try to frame you?"

"No. Not in this hemisphere, at any rate."

"So, does that mean…" He trailed off as Willow became aware of chirpy, upbeat music playing softly somewhere in the room. Lestrade glared briefly at Sherlock, who appeared not to notice.

Lestrade cleared his throat and said, in a louder voice, "So you can think of someone who might want to… discredit you? Any enemies at all?"

"Well…" Willow paused. There were demons and vampires galore in Sunnydale, and somewhere in the world roamed Jonathan and Andrew (but they probably wouldn't risk angering her a second time). But how would she begin to explain that her worst enemies were the monsters most only knew of as bedtime stories?

"I mean… I don't know if you knew, but Sunnydale was a bit of a… rough neighbourhood." She said carefully. "There's a long and not-very-specific list."

"…I see. And how-"

Suddenly the music grew much louder. Sherlock didn't even flinch, his blank gaze firmly on the screen. Willow found the music familiar…

Lestrade visibly ground his teeth. "Sherlock," He said softly. "Are you playing… Angry Birds?" He glared at his companion with a mixture of anger and incredulity.

Sherlock shrugged. "I'm bored! This line of questioning is utterly pointless, and as you won't let me do anything actually useful, this seems like a relatively pleasant alternative."

"If you're just going to mess around here, then get out."

"No, because if I leave then whose going to make sense of the little we do learn here? _You_?" He scoffed unpleasantly.

"Now look here-"

Before their argument could escalate further, the door swung open violently. The three occupants of the room looked up in alarm as two people in police uniform, a man and a woman, entered.

"Hey!" Lestrade exclaimed as he jumped to his feet. "What do you think you're doing? We're in the middle of an interrogation here!"

The woman stepped forwards and offered him a small cars that was obscured from Willow's line of sight. "Sorry, sir. Mycroft's orders. Willow Rosenberg is to be moved to a more secure area."

Willow groaned inwardly. Things just kept getting worse. Behind her eyes she felt the all-too familiar and seductive fluttering of dark magic, probing her defenses for weaknesses. She shuddered.

"What? Just how secure do we need one suspect to be? We followed Mycroft's last orders to the letter!"

Sherlock's head whipped round in something resembling outrage. "This ridiculous security was my _brother's_ orders?"

"Well, yes." Lestrade admitted. As Sherlock's frown deepend he hurriedly added, "You didn't need to know. You'd have gone and done something reckless just so he didn't get his way."

"Those sound like Mycroft's words."

"They are."

"Um, excuse me?" Willow said tentatively as the policeman unlocked her handcuffs and pulled them free of the table, before refastening them around her wrists. "Where am I going?"

"Sorry, Miss. You'll find out when you get there."

"Can I talk to Giles? Please, he needs to know what's happening. He'll know what to do." Willow insisted. The policeman shook his head. "Can't do that yet. He'll be notified once the situation is under control."

Lestrade paced along the back wall. "So, what? Is this it? Mycroft's just plucking suspects and witnesses from my investigation now? Is this even still my case?"

"All we were told was to move Miss Rosenberg, sir. I assume that the case remains yours."

Lestrade scoffed and glared at the wall, while Sherlock kept his silence. He gave Willow a final calculating glance as she was guided from the room.


End file.
